Timing device



TIMING DEVICE Filed Oct. 12, 1938 2 sheets-sheet 1 INVENTOR. JohnFZO/tSOfL BY W ATTORNEY$ 3 Dec. 16, 1941. R O 2,266,014

TIMING DEVICE Filed Oct, 12, 1938 v 2 Sheets-Sheet 2 INVENTOR.

\\ *rJ/u/L Exuc/zsow 1 BY z M ATTORNEYS.

Patented Dec. 16, 1941 UNHTED STATES PATENT GFEHCE 2,266,014 rnmvennvrcnJohn Erickson, Chicago, Ill. Application October. 12, 1938, Serial No.234,602 28 Claims. (01. 161-16) The present invention relates ingeneralto improvements in timing devices, and as shown herein comprises a newand improved timing device for an automatic bread toaster. The inventionis not confined to automatic toasters, however, as

- it provides a timing device capable of use in a variety of situationswhere the accurate and reliable measurement of a comparatively shorttime interval is desired.

The invention and the various features thereof will be describedhereinafter with reference to the accompa yi g drawings, in which- Fig.1is a section through a well known typeof automatic toaster, showing aside view of the timing device as installed;

Fig. 2 isa partial section through the same toaster, showing the timingdevice from the front;

Fig. 3 is a section through the timing device,

showing certain parts that cannot be seen clearly inFigs. 1and2;

Figs. 4 and 5 show modified forms oi the ma netic structure shown inFig. 3;

Fig. 6 is a front view of a somewhat different :iorm of timing devicewhich may be substituted for the one shown in Figs. 1,2, and 3;

Fig. 7 shows a side view of the disc 2 l 6, forming part of the timershown in Fig. 6; and

Fig. 8 is a diagrammatic circuit drawing of an automatic toasterequipped with a timing device according to the invention.

Referring first to Figs. 1, 2, and 3, the automatic toaster and timingdevice therein shown willbe described. v i

As mentioned hereinbefore, the automatic toaster to which the inventionis applied may be of well known construction, ofthe type shownanddescribed in the United States patent to Forbes, No. 1,665,735, forexample. As this toaster is fully disclosed in the patent, only so muchV thereof as is necessary to explain the operation of the timing devicein controlling the toaster is shown herein.

The toaster comprises a base I, an outer casing 32 supported on the baseand including the front cover 14, and the top 6|. ing is an inner casingcontaining the heating elements and defining a toasting chamber. Theinner casing includes two side walls such as 30, Fi s. 1 and 2, whichare spaced away from the outer wall 32, a front end wall 3|, and a rearend wall (not shown). There is a considerable space between the frontcover 14 and the front end wall 3! of the inner casing in which thetiming device and certain other operating parts are Within the outer08,59

threaded and fitted with nuts at both ends, asv

located. Fig. 1 is a section taken between the Fig. 2 is a partial frontview with the frontcover N removed, exposing the timing device and otherparts.

Within the toasting compartment there is located a slice support havingsheet metal bottom members which include vertical sections 4| extendingthrough slots vMl in the front end wall 3|. These sections 4| arerigidly secured to the bracket 66 by means of spacers 65 and two rodsshown. The bracket 66 is slidably mounted on' a vertical rod or post 8I, and is moved up and down on said post to raise or lower the slicesupport by means of a horizontal rod 96. The latter is rigid- 1y securedto a lever 89, which is located between the left hand inner and outerside walls of the casing, and which is similar to lever I 22,Fig. 1.This lever 89 is equipped with a coil spring which tends to raise thelever and the slice support. When the lever 89 is depressed, the slicesupport is lowered to the position shown in Fig. 2, where it isretainedby the engagement of the extension 68 on bracket 66 with the detent 69.The-latter is controlled by the timing device in a manner which will beexplained in detail.

'I'he foregoing-brief description of the toaster will be suflicient toenable the main features to be understood, which is all that isnecessary for an understandingof the timing device itself and the mannerin which it cooperates with the toaster. Further details regarding thetoaster construction may be had by referring to the pre- I, which arerigidly held together by square posts or spacers 8 and 9 at the bottomand I2 at the I top. The latter is omitted from Fig. 2 to avoidobscuring other parts. The Plates may be secured to these posts by meansof countersunk machine screws. There are also two cross members Ill andII, on which the electromagnet l3 is mounted, which afford additionalrigidity to the frame. The frame issecured to the toaster by means oftwo'ears 6 and I, Fig. 1, which overlap the side wall 30 and arefastened to it by screws,

as shown, and by'means of a bent-over portion 5 of frame plate 3, whichis fastened to the base I by a screw, asshown in Fig. 2.

The shaft l5 has bearings m the name plates 3 and l and carries the gearwheel 16 inside the frame and the pinion l1 outside the frame. The

latter is clearly seen in Fig. 1. Both the gear I6 and pinion I1 arefixed to the shaft. The pinion I1 is engaged by the rack 24, which isheld against the pinion by two rollers 2I and 22. These rollers aresupported in a U-shaped frame 29, one side of which, indicated at I9,extends to the rear and is pivoted on the shaft I5 between the pinion I1and the frame plate 4.

The rack 24 is pivoted on the lever I at 23, and the-lever in turn ispivoted on the rod 9| which extends through both side walls of the innercasing. The end of the lever extends out The usual adjusting device forthe timer comfront cover 14 by means of the spring I35. This adjustingdevice is fully disclosed in the patent.

The shaft is fixed in frame plates 3 and 4. Rotatably mounted on shaft25 is a wheel or disc 31 which is carried on the hub 26. The wheel 21 isof magnetic material (iron or soft steel) and has a smooth periphery.Alongside the wheel 31 there is a combination pinion and ratchet wheel38, which is rotatable on shaft 25. The pinion section is in engagementwith gear wheel I6, while the ratchet section is engaged by a pawl inthe form of a fiat spring 36. The latter is supported on a stud 35 whichis fixed to the wheel 31. From the foregoing it will be seen that thepinion 38 can rotate in a clockwise direction, as seen in Fig. 3,independent of the wheel 31, but when the pinion is rotated in acounterclockwise direction, it will drive the wheel 31 through themedium of the ratchet and the spring or pawl 36.

Associated with the wheel 31, is an electromagnet comprising a core I4and coil I3. The core of the magnet is supported on the two crossmembers I6 and II by means of small machine screws. The magnet has twoarmatures' and 46, supported on stifi springs 43 and 44, which aresecured to spacers 8 and 9, as shown. These springs have practically notension, just enough to hold the armatures 45 and 46 in light contactwith the periphery of wheel 31. The magnetic circuit includes the coreI4, the armatures 45 and 46, and the wheel 31. To avoid short-circuitingof magnetic flux the spacers I0 and II and the frame plates 3 and 4should be of nonmagnetic material.

The spring 44 has an extension or tongue 41, which is engaged by abi-metallic strip 48 secured to the end wall ill of the inner casing.When the toaster is cold this bi-metallic strip is under considerabletension and presses the armature 46 against the wheel 31. Also mountedon the end wall of the inner casing is a pair of contact springs 49 and56 which are normally held closed by the bi-metallic strip 58. The strip58 and the contact springs 49 and 56 are supported on a bracket 59.

The detent 69 forms part of a bell crank lever which is pivoted on apart 5I ofv frame plate 8. The lever passes through plate 3 behind part5I and has a horizontal arm or trigger portion 52 through which the endprojects into the path of lever I26. In the drawings, Figs. 1 and 2, the

' switch comprising contacts 16 and 11.

which lies in a slot 53 in the frame plate 4,.

lever I20 is shown just as it engages the trigger 52 in its upwardmovement under the force applied by spring 34. As the lever moves upwardfrom the position in which it is shown, it rotates the bell crank leverand moves detent 69 out of the path of the extension 68, which releasesthe slice support. Shortlyafter this occurs, the trigger 52 engages theupper end of the slot 53, and further movement of lever'I2Il isprevented.

The circuit connections for the complete toaster are shown in Fig.8. Theconductors 21 and 28 are conductors of the usual flexible cord andconnect to terminals at the rear of the toaster. The heating elements I8and I8 are bridged across these terminals in series with the switchcontacts 16 and 11, which are open or closes, depending on the positionof lever 89, as described in the Forbes patent. The magnet winding I3 isof high resistance and is connected in parallel with the heatingelements. As intimated above, I8' may be a short section of the usualheating winding, or it may be an additional heating winding having itscoils interspersed with those of the usual winding. A separateresistance may also be used, and in this case it may be inductive. Theelement I8 is normally shortcircuited at contact springs 49 and 58, andis connected in the circuit by opening of the contact at these springsunder control of the bimetallic strip 58.

. The operation of the timing device in timing a toasting interval willnow be described. It will be assumed that the operating levers I22 and89 are both in their extreme upper positions, which is the normalcondition. The cord 21- -28 may now be plugged into a convenient outlet,which gives access to commercial alternating current. -A couple ofslices of bread are next inserted in the slice support, after whichlevers 89 and I22 are depressed.

The operation of lever 89 lowers the slice support into toastingposition and also closes the Current is thus supplied to the heatingelement I8 and to the magnet winding I3. As the lever I22 has beendepressed also, the trigger 52 will be free and the extension 68- willengage the detent 69, locking the slice support in toasting position inknown manner. 1

The depression of lever I22, or I26, releases the trigger 52 aspreviously mentioned, tensions the coil spring 34, and rotates thepinion I1 through the medium of the rack 24. The pinion rotates shaft I5and gear I6, and the latter rotates the pinion 38. The direction ofrotation is olock wise as seen in Fig. 3. Dueto the ratchet connectionbetween the pinion and wheel 31, this rotation of the pinion can takeplace freely notwithstanding that the wheel 31 is prevented fromrotating at this time. The lever I22 is depressed as far as it will go,the downward movement being limited by engagement with the handle I25 ofthe adjusting device. When the lever is released, it attempts to riseunder the influence of spring 34, but such movement entails thecounterclockwise rotation of pinion 38, which cannot take place withoutrotation of wheel 31. Since the wheel 31 is locked against rotation thelever I22 remains stationary in depressed position for the time being. 7

When the toaster is started up froma cold condition as assumed in theforegoing, the wheel 31 is prevented from rotating not only by anelectromagnetic locking action which will be described,

but also by the bi-metallic strip 48, which presses .aaeaom wheel. Thispressure on the wheel, in cooperation with the magnetic effect, issufficient to entirely prevent the wheel from rotating. The strip 48 issecured directly to the inner casing, however, and also receives heatdirectly from the toasting compartment through slot II, and heats upquite rapidly, therefore, with the result that it bends toward thecasing and frees the armature 46. The strip 48 should be so arrangedthat this action will take place in about 20 secends or thereabouts,depending on the characteristics of the toaster. When fully heated, thestrip 48 will close the slot 'II, and prevents the escape of heated airinto the timing compartment.

As soon as the wheel 3'! is released by the bimetallic strip 48, itbegins to rotate slowly from power supplied through the gear train byspring 34. The energization of coil I3 causes the armatures 45 and 46 togrip the rim of wheel 31 firmly; but twice in each cycle, or 120 timesper second (if 60-cycle current is used) the current in the coil willfall to zero and reverse, and the direction of flux in the magneticcircuit will reverse. At each reversal thewheel 31 is momentarilyreleased, but is instantly gripped again by the armatures 45 and 46. Dueto the inertia of the parts and to the very short time interval duringwhich movement is permitted, the angular distance which wheel 31 movesat each current reversal is minute, and the rotation of 'wheel 31 takesplace very slowly. a

It follows from the foregoing that the lever I 22 will rise slowlyduring the timing operation, under control of wheel 31 and theassociated electromagnet, and will eventually engage trigger 52 and moveit upward. The bell crank lever is accordingly rotated on its pivot, anddetent 69 is moved out-of the path of extension 68, releasing'the slicesupport, which rises to non-toasting position. At the same time theswitch comprising contactsIB and TI is opened and the current is cutoff.

After the toasted slices of bread have been removed, two more slices ofbread may be inserted and the toasting operation may be repeatedimmediately. Levers 89 and I22 are both depressed as before and with thesame result, except that in this case the timing device begins tofunction as soon as lever I 22 is released, for the bi-metallic strip 48has not had time to cool 0E. The second toasting operation is thereforeterminated after a shorter-interval than the first. Immediatelysucceeding toasting operations are timed the same as the secondoperation. However, if there is a substantial delay, enough to allow thetoaster to cool down to such an extent that a longer time interval isrequired to complete a toasting opera-' tion, the bi-metallic strip willalso cool off and will lock the timing device to delay starting thereofin the manner explained, thereby increasing the next toasting intervalto the requisite extent.

In further explanation of the foregoing, I have determined by experimentthat an automatic toaster of this type will heat up on the firsttoasting operation to a temperature which is substantially as high asthe temperature which it reaches on subsequent operations. Furthermore,in the practical use of a toaster of this kind, when more than twopieces of toast are to be made, the successive toasting operationsgenerally follow each other in quick succession, so that at the start ofeach operation the toaster is always cold or by merely providing meansfor suitably lengthening the first toasting interval each time thetoaster is started up cold. The arrangement comprising the bi-metallicstrip 48 accomplishes this object in a very satisfactorymanner.

It is recognized, nevertheless, that a slight further temperature risedoes take place during successive toasting operations until a maximumtemperature is reached. This rise in temperature ordinarily will notcause appreciable difference in the toast, unless augmented by otherfactors such as a higher than normal voltage of the curjustment is suchthat before-an excessive temperature is reached the contacts 49 and 50are allowed to separate and resistance I8 is connected in series withthe "heating element I8. -As a result the current consumption isloweredslightly, and further rise in temperature is prevented.

The timing device just described is surprisingly accurate. The rim ofwheel 31' should be smooth and polished; likewise the pole faces ofarmatures 45 and 46. There may be a direct ironto-iron contact at thewheel, as shown, but air gaps should be provided at some point in themagnetic circuit, as between the armatures and the core of the magnet.

In the design of the timing device, it is desirable to have the magnetof relatively high resistv ance so as to consume little current. Thewinding interval.

ing I3 may therefore include considerable re-' sistance wire, onlyenough copper being used to give the requisite number of ampere turns.

: .The spring 34 must have suflicient power to reliably trip themechanism at the end of the toast- The power of the magnet and size ofspring 34 being determined in this manner, the desired time interval issecured by giving the wheel 31 the proper weight, which is determined byexperiment in any given case, and by using the proper gear ratioin thegear train.

In the event that the timing deviceis to be used for some purpose thatrequires. the rate of the timing device to be changed, this can be takencare of by interchangeable or adjustable weights for the wheel 31, whichcan be inserted in the threaded openings with which wheel 31' isprovided, as shown in Fig. 3. The weights may be plain cylindricalplugs, threaded at one end. In the case of an automatic toaster, it isdeemed preferable to make the wheels 31 of a uniform weight, calculatedto give the proper time interval, and then adjust the toaster for lightor dark toast by means of a device such as I25, which varies the lengthof theme through which lever I22 is operated.

The timing device is substantially noiseless. The armatures 45 and 46 donot have any noticeable vibration,and rest at all timeson the rim ofwheel 31.

Fig. 4 shows a modified magnetic structure, in-

which the wheel 31' is not necessarily included in the magnetic circuit,and may be made of nonmagnetic material if desired. That is, in thisthat a good uni form product can be turned out section 22L form of theinvention the wheel 81' may be either of magnetic or non-magneticmaterial. As shownin the drawings, the structure includes the core I4,the coil l8, armatures 3M and 302 which are pivoted on the core, and amember 303 of magnetic material which completes the magnetic circuit.The armatures are provided with bearing faces :04 and 305 which may bemade of hard fiber, for example, and which rest against the rim of wheel31'.

Fig. 5 shows a further modification employing a thin, fiat disc 3I0,which may be of non-magnetic material. The coil 3I3 has a core made oftwo iron or' steel stampings which overlap each other throughout thelength of the coil, as shown. The ends of these core stampings' arelocated on opposite sides of the disc M and are in loose contact withit. The interposed disc forms a gap in the magnetic circuit;

The operation of the modified structures shown in Figs. 4 and is similarto that of the structure shown in Fig. 3 and accordingly will beunderstood without further explanation.

Referring now to Figs. 6 and '7, the modified timing device shown inthese figures will be described. The parts are mounted in a frame whichcomprises plates 2M and 202, and two spacers such as 203 at the top andother spacers such as 204 at the bottom, by means of which the platesare rigidly supported in spaced relation as shown.

Rotatably mounted in the frame is a shaft I5,

' on which are supported the gear wheel I6 and the pinion II'. Theseparts are similar to the correspondingly numbered parts in Fig. 2. 1

Beneath the shaft I5 there is a shaft 2l8' which is fixed in the frame.'Next to frame plate in disc 2 I 8, with a predetermined amount of play.The opening 230 may be, for example, .002 of an inch larger than thestud 2H and the other openings 23l, etc., may progressively increase insize by .002 of an inch.

Supported on-two brackets such as 205 there is a magnet core 201 havinga winding 208. Just above the magnet is a cross member 209 on which ispivoted the armature 208 by means of a shoulder screw 2I0. The end ofthe armature which is opposite the magnet is bifurcated and comprisestwo slightly resilient members which extend between the discs 2I5 and2I0 as shown. The bifurcated end of the armature is urged to the rightby a spring 2l2 and normally clamps the disc 2I5 tightly against thefixed stud 2. In this position of the armature it is just out of contactwith disc .2I6, which is accordingly free to move between the armatureand the adjusting screw 2 I3, except that its movement is prevented bythe stud 2Il on disc 2I5.

202 there is rotatably supported on the shaft 2l8 a combined ratchetwheel and pinion comprising a hub 2I9, a pinion section 220 and aratchet About the center of the shaft there is rotatably supported a hub229 on which is mounted a disc 2I5. This disc has a stud 221 rigidlyfixed to one side for the purpose of supporting the pawl 228. This pawlmay be a flat spring and engages the ratchet section 22l on the rearside thereof as it is shown in the drawings.

Adjacent the frame plate 20I there is rotatably mounted on theshaft 2l8a member comprising the head 222 and a threaded portion 226, the saidmember also having a short octagonal portion next the head on which thedisc 2I6 is mounted. The disc 2I5 is also shown in Fig. '7, from whichit will be seen that it has an octagonal openingat the center. The disc2I6 lies against the head 222 and is held in position by The disc 2I5 isarranged to be rotated by a flexible connection to the hub 228 on whichdisc.

2I5 is mounted. This connection comprises a spring 224, the inner end ofwhich is secured to the hub 229 and the outer end of which is fastenedto a pin 223 which projects to the right from the head 222. The spring224 is arranged so that it will be wound or tightened bycounterclockwise rotation of disc 2I5, as seen from the right.

, The disc 2l8 .is also mechanically associated with the disc 2I5through the medium of a stud 2". This member is rigidly fixed to disc2I5 and passes through one of the openings, such as 230 or 2, in disc2l6. The stud 2 is accurately of hardened steel and fits in the openingThe foregoing describes the essential parts of this form of the timingdevice, which obviously can be substituted in the toaster shown in Fig.1.

In the drawings, Fig. 6, the rack which operates with pinion II' and thetrigger mechanism for tripping the slice carrier have been omitted,

but these parts may be the same as shown in Figs. 1 and 2.

Describing the operation now, when the operating lever I22 is depressed,the rack rotates the pinion I1 and gear I6 in a counterclockwisedirection as viewed from the right. Gear I6 ropressed along with leverI22, and lowers the slice support, also closing the circuit to theheating element and to the magnet winding 206. On energizing, themagnet-attracts armature 208, which releases disc 2I5 and at the sameinstant clamps disc 2H5 against the end of screw 2I3. When the disc 2I5is released, it rotates slightly in a counterclockwise direction as seenfrom the right until stud 2II engages the other side of the opening indisc 2H5. Disc 2I5 can rotate no farther because disc H6 is now clampedagainst rotation. When the magnet deenergizes, the spring 2I2 instantlyforces the bifurcated end of the armature 208 to the right, whichreleases disc 2I8 and at the same time clamps disc 2I5 against rotation.When disc 2I6 is released by the deenergization of the magnet, itfollows disc 2I5; that is, it rotates under the influence of spring 224and takes up the play between the stud 2II and the opening in the disc.A

' The operation continues as described, the magnet being energized ateach half cycle to permit a slight advance of disc 2I5 and deenergizingeach time the current reverses to permit a corresponding advance of disc2I6. The tension in spring 2I2 should be adjusted. with reference to thepower of the magnet so as to insure that theand a brakemember engagingthe periphery is not critical, however. The stroke of the armature isextremely short and this feature, together with the slight resiliency inthe end members of the armature insures that on the energization of themagnet the disc 2H5 is clamped at the same time that the disc H isreleased, or at any rate before the stud 211 can complete its movementwithin the opening in disc 2l6.

From the foregoing it will be seen that the disc 2 IE will rotate inminute steps the length of which is determined by the difference betweenthe diameter of the stud 2i! and the diameter of the opening in disc M6.The disc accordingly rotates at a slow rate, permitting gear l6 andpinion II to rotate, which is accompanied by the rising of lever I22.The lever eventually trips the slice support to terminate the toastingoperation in the manner previously described.

For an automatic toaster such as described herein, the size of theopening in disc 2l6 will depend on the gear ratio between gear I 6' andpinion 220 and on the number of revolutions of pinion I1 within theadjustment range of lever I22. To show how this works out, it may beassumed that the opening in disc M6 is larger than the stud 2|! by .006of an inch. The disc 215 will therefore advance this distance 120 timesper second, or .72 of an inch in one second, and 43.2 inches in oneminute. If the opening is located on a circle, the circumference ofwhich is 5 inches, the disc will rotate 8.64 times per minute, and ifthe gear ratio is 4 to l, the gear l6 and pinion II will rotateapproximately two times per minute. Since the toasting interval for atoaster of this type is about a minute and a half, or somewhat less, itwill be seen that about three rotations of pinion l'l' will be required,which is conveniently within the range of movement of the lever I22.

It will be clear from the foregoing that by making the discs M5 and 216slightly larger and by using a smaller opening in disc 2T6 the gearreduction can be dispensed with.

When the timing device is used for other purposes, it may be necessaryor desirable to change the rate, and to enable such change to be readilyaccomplished the disc 2| 6 is provided with a plurality of openings ofdifferent sizes, as shown in Fig. '7. In order to effect the change, thenut 225 is backed off, the screw M3 is partly unscrewed, and the disc H6is then moved to the left far enough so that it can be rotated to theproper position to bring the stud 2|1 in line with the desired'opening.The openings may be marked in accordance with their sizes. After thedisc 2H5 has been assembled as desired the nut 225 is tightened up againand screw 213 is readjusted.

This form of timing device, likethe one shown thereof, and a windingenergized by alternating current for setting up an alternating magneticflux in said circuit to thereby produce an intermittent response of thewheel to said driving means. V

2. In a timing device, a reciprocating member, a spring in which poweris stored when said member is moved in one direction, said springtending to restore said member, a rotatable member, means whereby saidreciprocating member'rotates said rotatable member when thereciproacting on said rotatable member, said brake being energized byalternating current and effective to prevent rotation of said rotatablemember except when the current changes direction.

" 3. In a timing device, a rotatable disc or wheel,

an electromagnet, movable pole pieces for said magnet engaging oppositepoints on the periphery of saiddisc, means for applying power to rotatesaid disc, and meansfor'energizing said magnet by alternating current.whereby said pole pieces prevent rotation of the disc except at timeswhen the current falls to zero.

4.'In a timing device, a rotatable member, a setting member, meansincluding a gear train connecting said rotatable member with saidsetting member, a ratchet included in said means permitting operation ofsaid setting member while. the rotatable member is stationary, a springfor returning said setting member and for driving said rotatable memberthrough said gear train and ratchet, a magnet, an armature for saidmagnet engaging said rotatable member, and means for energizing saidmagnet by a1ter nating current, whereby the said rotatable member ispermitted to advance in short steps under control'of said armature.

5. In a timing device, a rotatable member, means for driving saidmember, an electromagnet, stationary armatures for said magnet engagingsaid member on opposite sides thereof,

, and means for energizing said magnet by alterin Figs. 1, 2, and 3, issubstantially noiseless. It

is entirely accurate; that is, the ,timing device itself is accurate,and errors can occur only by reason of variations in the frequency ofthe current supply. This form of the invention may therefore be usedwhere very exact timing is of magnetic material, means for driving saidwheel, a magnetic circuit including said wheel nating current to causesaid armatures to alternately lock and release said member whileremaining in engagement therewith.

6. In a timing device, two rotatable members, resilient means wherebythe first member drives the second member, electromagnetic meansenergized by alternating current for alternately frictionally clampingand releasing said members, and means whereby each member when clampedlimits the movement of the other member when released. v

7. In a timing device, two discs rotatable side by side On a, commonshaft, each disc having a uniform uninterrupted circular surface, amovable member adapted to engage said surfaces, means for rotating thefirst disc, a flexible connection through which the first disc drivesthe second, a pin or stud fixed to one disc and extending through anopening in the second disc, said opening being larger than said pin; andmeans including said member for alternately clamping and releasing saiddiscs, whereby each disc rotates when it is'released to an extentdetermined by the difference in the diameter of said pin and saidopening.

8. In a timing device, a rotatable member, means for applying power todrive said member, and means for causing said member to respond to theapplied power in minute steps, said means including an electromagnetenergized by alternating current, a core for said electromagnet, anarmature forming a non-rigid extension of said magnet core and engagingsaid rotatable member, and 'means for holding said armature againstrotation with said member.

9. In a bread toaster which includes a slice carrier having toasting andnon-toasting positions, means for locking said slice carrier when movedto toasting position, a timer including a moving part adapted to tripsaid locking means in a certain position, a rotatable member controllingmovement of said part toward tripping position, and electromagneticmeans energized by alternating current for controlling the movement ofsaid rotatable member.

10. In a bread toaster which includes a slice carrier having toastingand non-toasting positions, means for locking said slice carrier whenmoved to toasting'position, a timer including a rotatable member, meansfor driving said member, a magnetic brake. energized by alternatingcurrent for controlling the rotation of said member. and means operatedby said member for tripping said locking means.

11. In a bread toaster which includes a slice carrier having toastingand non-toasting positions, means for lockingsaid' slice carrier when.moved to toasting position, a lever manually operable to timingposition, a spring connected to said lever for restoring the same,tripping means ance with the length of said time interval, meansforrotating said disc on its axis, and means including saidelectromagnet for preventing rotation of said disc except during a shortinterval each time when the current in said magnet changes direction,the amount which said disc rotates each time depending on its inertia.

16. In a timing device for measuring a predetermined time interval, anelectromagnet energized by alternating current, a wheel or disc thediameter of which is predetermined in accordance with the length of saidtime interval, means for rotating said disc on its axis, and

braking means operated by said electromagnet for preventing rotation ofsaid disc except for a short intervaleach time when the current inengaged by said lever on restoring, a rotatable partment through whichsaid strip receives heat which is adapted to be closed by the strip uponheating.

13. In a timing device, an electromagnet, an armature for said magnet, arotatable member having a continuous circular surface concentric withits rotation axis and engaged by said armature, means for applying powerto rotate said member on its said axis to move the said surface thereofcontinuously past said armature always in the same direction, and meansfor energizing said magnet by alternating current to cause said armatureto exert a pressure against the said surface, the driving power and thepower of said magnet being so related that the said member is unable torotate in response to the driving power; except for a brief instant eachtime when the current falls to zero.

14. In a timing device, a wheel ordisc supported for rotation on ashaft, means for applying power to. rotate said disc, an electromagnetenergized by alternating current, means including said magnet forlocking the disc against rotation except for a short interval each timethe said electromagnet changes direction, said braking means including apart engaging the wheel at or near its periphery, whereby the number ofrotations made by the disc during said time interval will depend on itsdiameter.

, 17. In a timing device, a rotatable member,

means for applying power to rotate said member, means for causing saidmember to respond to the applied power in minute steps, said meansincluding an electromagnet energized by altemating current, an armaturefor said magnet, and a brake member actuated by said armature andengaging said member, and means responsive to a predetermined extent ofrotation by said member for interrupting the supply of alternatingcurrent to said magnet. 18. In a bread toaster, a heating element, meansfor supplying current to said element, a timer including a rotatablemember, means for driving said member, a magnetic brake energized byalternating current for controlling the rotation of said member, andmeans controlled by said member and responsive to a predetermined amountof rotation of said member for interrupting the supply of current tosaid element.

19.. In a bread toaster, a timer including a rotatable member, means forstoring power to drive said member at the time a toasting operation isstarted, a magnetic brake energized by alternating current forcontrolling the rotation of said member, and means responsive to apredetermined amount of rotation of said member for terminating thetoasting operation.

20, In a timing device, a wheel or disc controlling the operation of thetimer, means for rotating said disc, an electromagnet energized byalternating current, a magnetic circuit including an armature for saidmagnet but excluding said disc, and a brake member pressed against saiddisc by said armature with sufllcient force to current in the magnetreverses its direction, the

' ergized by alternating current. a wheel or disc the weight of which ispredetermined in accord-- prevent rotation of the disc except for abrief instant each time when the current in the magnet winding changesdirection.

21. In a timing device, a thin, flat disc, means for rotating said discabout an'axis coincident with the center thereof, an electromganetenergized by alternating current, said electromagnet including polepieces extending in overlapping relation on opposite sides of said discnear the edge thereof and in continuous contact therewith, said polepieces being effective to grip the edge of the disc between them andprevent rotation of the disc when the electromagnet is energized and torelease the disc momentarily each time the magnet is deenergized.

22. In a timing device, a rotatable disc, means for rotating said discabout an axis coincident with the centerthereof, a magnetic circuitincluding a portion passing through the disc in a whereby the disc ispermitted to rotate in short steps without chattering of said armature.

24. In a timing device, two rotatable members, means for applying powerto rotate one of said members, speed-changing means coupling saidmembers together, control means operated responsive to a predeterminedrotation of the slowest rotating member, a braking device controllingthe rotation of the fastest rotating member, said braking deviceincluding a parthaving a smooth surface in continuous engagement with asmooth circular surface of the said last mentioned member, and a magnetwinding energized by alternating current foroperating said brakingdevice.

25. In a timing device, arotatable disc, means for rotating said disconan axis coincident with the center thereof, an electromagnet, meansincluding anarmature for said magnet for clamping the edge of said discagainst a fixed support,

for energizing said magnet by alternating current, whereby the disc isintermittently released. 26. In a timing device, a rotatable disc, meanscluding an armature for said magnet for clamping the edge of said discagainst a flxed support, thereby preventing rotation of the disc, meansfor energizing said magnet by alternating current, whereby the disc isintermittently released, andmeans under the control of said magnet forlimiting the extent to which said disc can rotate each time it isreleased.

27. In a bread toaster which includes a slice carrier having toastingand non-toasting positions, means for locking said slice carrier when:moved to toasting position, a timer including a member movable in apredetermined path, means for driving said member, a magnetic brakeenergized by alternating current for controlling the movement of saidmember, said brake including cooperating brake surfaces in continuousengagement, an electromagnet, anda stationary armature controlling thepressure with which said'surfaces engage each other, whereby said membermoves only during each reversal of said alternating current, and meansoperated by said member for tripping said locking means. s

28. In a bread toaster, a timer including a movable member, means forstoring power to movesaid member at the time a .toasting operation isstarted, a magnetic brake energized by alternating current forcontrolling the movement of said member, said brake includingcooperating brake surfaces in continuous engagement, an electro magnet,and a stationary armature controlling the pressure with which saidsurfaces engage each other, whereby said member moves only dur-. mg eachreversal of said alternating current, and means responsive to apredetermined amount of movement of said member for terminating thetoasting operation;

i JOHN ERICKSON.

